For clarification, it is remarked that, in the present connection, use of the term brushes is supposed to include all articles which have a body member needled with bristles, wherein the size is not important. Thus, the term brushes includes very small brushes, for example tooth brushes, and also large brushes, for example street brooms.
In the classic manufacture of brushes, bristles are removed from a magazine by means of a separator, are folded in a stuffing tool, and are secured by means of wire in predrilled holes of a relatively thick-walled brush member. Machines are used for this (German Pat. No. 1 114 463), with which brush members can be rotated into various positions in order to be able to place bores in any desired directions and in order to be able to insert bristle bunches into these bores by means of wire. The free bristle ends are subsequently sheared off and cleaned out. Machines of this type are manufactured as twin automatic machines in order to increase the performance, on which machines four operations (drilling, stuffing, shearing off and cleaning out) are simultaneously carried out two times.
The operating speed of such machines is limited because, with a complicated sequence of movement, the brush members must be moved into three planes, wherein considerable moment of inertia forces must be overcome. The limit of the operating speed lies at aproximately 300 sequences per minute, and cannot be exceeded because of the necessary precision for the drilled holes.
Also known is a machine (U.S. Pat. No. 3,604,043) with which bristles which consist of a thermoplastic material are connected by welding to a brush member which consists of the same thermo-plastic material. The machine has a bristle magazine in which bristles which are cut to length are stacked. Sleeves are placed through holes which exist in the magazine wall, which sleeves sit on a holder and are filled with bristles when being placed into the magazine. The connecting ends of the bristles are thereafter slightly melted by means of a heating element. The brush member is also slightly melted at the fastening regions for the bristle bunches by means of a heating element and is subsequently welded simultaneously to several bristle bunches. The brush member of brushes which are manufactured in this manner can be designed with relatively thin walls in order to save material. Disadvantageous, however, is that it is not possible with the method to manufacture brushes of any desired shape, for example round-head brushes with a bristles over a range of 180.degree. or even 360.degree..
In a further conventional machine (U.S. Pat. No. 4,255,224), the brush member is moved into any desired position with the sequence of movement which is known from classic brush-manufacturing machines. The bristles which are cut to length are removed from the bristle magazine by means of a sleeve. The free ends of the bristles are slightly melted by means of a heating element, while at the same time the brush member is slightly melted with a different heating element at the intended fastening regions for the mentioned bristle bunches. After the heating element has swung out of the area between the brush member and bristle bunch, the bristle bunch is guided to the brush member and is welded thereto. With this, brushes of any desired shape with welded-on bristle bunches can be manufactured. The disadvantage of such machines lies in the expensive construction and the low output. In particular, the operating speed is limited, because a minimum amount of time is needed for welding on each bristle bunch, which minimum time is a multiple of the time needed for stuffing in a bristle bunch.
Also known is a method of the above-mentioned type (German Offenlegungsschrift No. 28 49 510) in which bristle bunches are either removed from a magazine of cut bristles or bristle bunches are separated from a strand and are guided through short guide channels to a brush member. The bristle bunches must here be gripped so that the individual bristles cannot separate from one another. With this, brushes can be manufactured in which the bristles point in various directions and all bristle bunches can be welded on simultaneously, so that a great manufacturing capacity is achieved. Of course, it is not possible with this method to secure bristle bunches in any desired direction on the brush member since, because of the necessity to hold the bunches together, the guide channels can only be short and therefore only small direction changes are possible.
Finally, a method is also known (German Offenlegungsschrift No. 29 22 877) in which bristle bunches are placed through a mold wall so that their connecting ends project into a mold cavity. The mold cavity is thereafter injected with a thermoplastic material for forming a brush member, wherein the bristle bunch ends which project into the mold cavity are enveloped by the injected plastic.
A basic purpose of the invention is to provide a method with which it is possible to efficiently manufacture brushes of any desired shape, for example brushes which are needled all around with bristles. A machine is also to be provided, with which this method can be carried out.